1. Field of the Invention
The present invention relates to apparatus for drivingly rotating a drum, for example, to an apparatus for driving a photosensitive drum for use in electrophotographic copying machines.
2. Description of the Related Art
Apparatus for drivingly rotating a hollow drum are generally provided with a flywheel for increasing the moment of inertia to obtain stabilized rotation. The publication of Japanese Laid-Open Patent Application No. 173780/1990, for example, discloses such an apparatus wherein a flywheel is provided inside a hollow drum.
On the other hand, in the case of drums which need replacement like the photosensitive drums of electrophotographic copying machines, the drum is removably coupled to the drum driving apparatus. However, the flywheel, if installed inside the drum, makes the drum extremely heavy, so that the drum is inconvenient to handle and can not be replaced efficiently.